Associations of cumulative exposure and dynamic patterns of the C-reactive protein-triglyceride-glucose index with cardiometabolic multimorbidity in middle-aged and elderly Chinese: a nationwide cohort study

With the rising prevalence of cardiometabolic multimorbidity (CMM), it has become a significant public health issue affecting the health of middle-aged and elderly populations. The C-reactive protein-triglyceride-glucose index (CTI), as a composite biomarker integrating inflammatory and metabolic information, currently exhibits unclear associations with CMM risk. This study aimed to examine the association of cumulative exposure and longitudinal changes of the CTI with the risk of CMM in middle-aged and older Chinese adults. This longitudinal study used data from the China Health and Retirement Longitudinal Study (CHARLS). Cox regression and restricted cubic spline (RCS) models were employed to assess the association between cumulative CTI (cuCTI) and CMM risk. The area under the ROC curve (AUC) was computed to evaluate the predictive performance of different indicators. Participants were classified into three groups based on CTI changes using K-means clustering. Subgroup and sensitivity analyses were conducted to test the robustness of the results. The study included 4,461 participants, among whom 514 (11.5%) developed CMM. CMM risk increased with higher cuCTI levels. In the multivariable-adjusted Cox regression model, participants in the highest tertile (Q3) had a 146% greater risk of CMM than those in the lowest tertile (Q1) (HR = 2.46, 95% CI: 1.83–3.31, P < 0.001). RCS analysis indicated a nonlinear relationship between cuCTI and CMM risk (P for nonlinearity = 0.015). K-means clustering identified three distinct CTI longitudinal changes. Both the moderate growth change cluster (Cluster 1) and the persistent high-risk change cluster (Cluster 2) were associated with significantly elevated CMM risks (HR = 1.89, 95% CI: 1.47–2.44; HR = 2.37, 95% CI: 1.73–3.24, respectively). This study demonstrates that both cuCTI and changes in CTI are associated with the risk of CMM, and that a high level of cuCTI increases CMM risk in middle-aged and older Chinese adults.